| .\" |
| .\" mountd(8) |
| .\" |
| .\" Copyright (C) 1999 Olaf Kirch <okir@monad.swb.de> |
| .\" Modified by Paul Clements, 2004. |
| .TH rpc.mountd 8 "31 Aug 2004" |
| .SH NAME |
| rpc.mountd \- NFS mount daemon |
| .SH SYNOPSIS |
| .BI "/usr/sbin/rpc.mountd [" options "]" |
| .SH DESCRIPTION |
| The |
| .B rpc.mountd |
| program implements the NFS mount protocol. When receiving a MOUNT |
| request from an NFS client, it checks the request against the list of |
| currently exported file systems. If the client is permitted to mount |
| the file system, |
| .B rpc.mountd |
| obtains a file handle for requested directory and returns it to |
| the client. |
| .SS Exporting NFS File Systems |
| Making file systems available to NFS clients is called |
| .IR exporting . |
| .P |
| Usually, a file system and the hosts it should be made available to |
| are listed in the |
| .B /etc/exports |
| file, and invoking |
| .B exportfs -a |
| whenever the system is booted. The |
| .BR exportfs (8) |
| command makes export information available to both the kernel NFS |
| server module and the |
| .B rpc.mountd |
| daemon. |
| .P |
| Alternatively, you can export individual directories temporarily |
| using |
| .BR exportfs 's |
| .IB host : /directory |
| syntax. |
| .SS The rmtab File |
| For every mount request received from an NFS client, |
| .B rpc.mountd |
| adds an entry to the |
| .B /var/lib/nfs/rmtab |
| file. When receiving an unmount request, that entry is removed. |
| .P |
| However, this file is mostly ornamental. One, the client can continue |
| to use the file handle even after calling |
| .B rpc.mountd 's |
| UMOUNT procedure. And two, if a client reboots without notifying |
| .B rpc.mountd , |
| a stale entry will remain in |
| .BR rmtab . |
| .SH OPTIONS |
| .TP |
| .B \-d kind " or " \-\-debug kind |
| Turn on debugging. Valid kinds are: all, auth, call, general and parse. |
| .TP |
| .B \-F " or " \-\-foreground |
| Run in foreground (do not daemonize) |
| .TP |
| .B \-f " or " \-\-exports-file |
| This option specifies the exports file, listing the clients that this |
| server is prepared to serve and parameters to apply to each |
| such mount (see |
| .BR exports (5)). |
| By default, export information is read from |
| .IR /etc/exports . |
| .TP |
| .B \-h " or " \-\-help |
| Display usage message. |
| .TP |
| .B \-o num " or " \-\-descriptors num |
| Set the limit of the number of open file descriptors to num. The |
| default is to leave the limit unchanged. |
| .TP |
| .B \-N " or " \-\-no-nfs-version |
| This option can be used to request that |
| .B rpc.mountd |
| do not offer certain versions of NFS. The current version of |
| .B rpc.mountd |
| can support both NFS version 2 and the newer version 3. If the |
| NFS kernel module was compiled without support for NFSv3, |
| .B rpc.mountd |
| must be invoked with the option |
| .B "\-\-no-nfs-version 3" . |
| .TP |
| .B \-n " or " \-\-no-tcp |
| Don't advertise TCP for mount. |
| .TP |
| .B \-P |
| Ignored (compatibility with unfsd??). |
| .TP |
| .B \-p " or " \-\-port num |
| Force |
| .B rpc.mountd |
| to bind to the specified port num, instead of using the random port |
| number assigned by the portmapper. |
| .TP |
| .B \-H " or " \-\-ha-callout prog |
| Specify a high availability callout program, which will receive callouts |
| for all client mount and unmount requests. This allows |
| .B rpc.mountd |
| to be used in a High Availability NFS (HA-NFS) environment. This callout is not |
| needed (and should not be used) with 2.6 and later kernels (instead, |
| mount the nfsd filesystem on |
| .B /proc/fs/nfsd |
| ). |
| The program will be called with 4 arguments. |
| The first will be |
| .B mount |
| or |
| .B unmount |
| depending on the reason for the callout. |
| The second will be the name of the client performing the mount. |
| The third will be the path that the client is mounting. |
| The last is the number of concurrent mounts that we believe the client |
| has of that path. |
| .TP |
| .BI "\-s," "" " \-\-state\-directory\-path " directory |
| specify a directory in which to place statd state information. |
| If this option is not specified the default of |
| .BR /var/lib/nfs |
| is used. |
| .TP |
| .BI "\-r," "" " \-\-reverse\-lookup" |
| mountd tracks IP addresses in the rmtab, and when a DUMP request is made (by |
| someone running showmount -a, for instance), it returns IP addresses instead |
| of hostnames by default. This option causes mountd to do a reverse |
| lookup on each IP address and return that hostname instead. Enabling this can |
| have a substantial negative effect on performance in some situations. |
| .TP |
| .BR "\-t N" " or " "\-\-num\-threads=N" |
| This option specifies the number of worker threads that rpc.mountd |
| spawns. The default is 1 thread, which is probably enough. More |
| threads are usually only needed for NFS servers which need to handle |
| mount storms of hundreds of NFS mounts in a few seconds, or when |
| your DNS server is slow or unreliable. |
| .TP |
| .B \-V " or " \-\-nfs-version |
| This option can be used to request that |
| .B rpc.mountd |
| offer certain versions of NFS. The current version of |
| .B rpc.mountd |
| can support both NFS version 2 and the newer version 3. |
| .TP |
| .B \-v " or " \-\-version |
| Print the version of |
| .B rpc.mountd |
| and exit. |
| .TP |
| .B \-g " or " \-\-manage-gids |
| Accept requests from the kernel to map user id numbers into lists of |
| group id numbers for use in access control. An NFS request will |
| normally (except when using Kerberos or other cryptographic |
| authentication) contains a user-id and a list of group-ids. Due to a |
| limitation in the NFS protocol, at most 16 groups ids can be listed. |
| If you use the |
| .B \-g |
| flag, then the list of group ids received from the client will be |
| replaced by a list of group ids determined by an appropriate lookup on |
| the server. Note that the 'primary' group id is not affected so a |
| .I newgroup |
| command on the client will still be effective. This function requires |
| a Linux Kernel with version at least 2.6.21. |
| |
| .SH TCP_WRAPPERS SUPPORT |
| This |
| .B rpc.mountd |
| version is protected by the |
| .B tcp_wrapper |
| library. You have to give the clients access to |
| .B rpc.mountd |
| if they should be allowed to use it. To allow connects from clients of |
| the .bar.com domain you could use the following line in /etc/hosts.allow: |
| |
| mountd: .bar.com |
| |
| You have to use the daemon name |
| .B mountd |
| for the daemon name (even if the binary has a different name). |
| .B Note: |
| hostnames used in either access file will be ignored when |
| they can not be resolved into IP addresses. |
| |
| For further information please have a look at the |
| .BR tcpd (8) |
| and |
| .BR hosts_access (5) |
| manual pages. |
| .SH SEE ALSO |
| .BR rpc.nfsd (8), |
| .BR exportfs (8), |
| .BR exports (5), |
| .BR rpc.rquotad (8). |
| .SH FILES |
| .BR /etc/exports , |
| .BR /var/lib/nfs/xtab . |
| .SH AUTHOR |
| Olaf Kirch, H. J. Lu, G. Allan Morris III, and a host of others. |